Stress exposure might disrupt many physiologic processes and lead to various health problems. Effective stress management strategies can help minimize or prevent detrimental stress consequences. By evaluating efficacy of stress reduction approaches and understanding mechanisms underlying their actions we can determine optimal strategies for preventing stress-related disorders. Aromatherapy is a complementary and alternative medicine (CAM) approach that has a great promise for stress management as a non-invasive, easy to use, and fast-acting therapy with no major side effects. Though aromatherapy is increasingly used for stress reduction, the evidence for its efficacy is scarce, and mechanisms underlying its action are unknown. The goals of this proposal are: 1) to evaluate efficacy of stress-reducing aromatherapy and 2) elucidate its mechanism of action. A randomized controlled trial will be conducted with 90 stressed older adults allocated to one of three groups exposed to either: 1) stress-reducing aroma, 2) detectable placebo aroma, or 3) non- detectable placebo aroma. Participants'physiologic stress markers will be assessed before, during, and after three laboratory stressors during a study laboratory visit. The assigned aroma will be given 5 minutes prior to onset of laboratory stressors. The physiologic measures of primary interest will include EEG frontal lateral asymmetry patterns and salivary cortisol levels. By comparing changes in physiologic markers in response to stressors among the groups experiencing different aromas, efficacy of aromatherapy will be evaluated. Further, half of the participants in each group will be assigned to receive a prime suggesting they are inhaling a powerful stress-reducing aroma. The mechanism of aromatherapy action, more specifically, the role of expectancy effects will be evaluated by comparing differences in stress response between: 1) the primed and non-primed participants and 2) participants exposed to detectable aroma and those exposed to undetectable aroma. We predict that efficacy of aromatherapy will be demonstrated, and both physiologic and expectancy effects will be shown to contribute to the aromatherapy mechanism of action.